Criminal Law and Procedure
Elements, Defenses, and Police Practices
Criminal law begins with actus reus and mens rea. Voluntary acts satisfy actus reus; status and involuntary conduct generally do not. Mens rea levels include purpose, knowledge, recklessness, and negligence. Accomplice liability requires intent to aid and actual aid; withdrawal must be timely and communicated. Attempt requires specific intent and a substantial step. Conspiracy requires agreement plus intent to achieve the objective, and many jurisdictions require an overt act.
Defenses include self-defense, defense of others, necessity, duress, insanity, and entrapment. Felony murder applies during inherently dangerous felonies, but the underlying felony must be independent. Transferred intent applies in homicide and battery contexts.
Criminal procedure focuses on the Fourth, Fifth, and Sixth Amendments. A seizure occurs when a reasonable person would not feel free to leave. Warrants require probable cause and particularity, but exceptions include search incident to arrest, automobile, plain view, consent, exigent circumstances, and inventory. Miranda warnings are required for custodial interrogation; invocation must be honored, and waiver must be knowing and voluntary. The Sixth Amendment right to counsel attaches at critical stages after formal charges, including post-charge lineups.
Traps and Rule of Thumb
Traps include treating a traffic stop as automatically a full search, missing the custody requirement for Miranda, and confusing pre-charge and post-charge counsel rights. Rule of thumb: ask whether the person was seized or in custody, then whether the search or interrogation was reasonable.